Method of manufacturing pressed material commutators

ABSTRACT

A method of manufacturing pressed material commutators comprising a hollow cylindrical shaped metal body, which is provided with a number of axial oriented groups of inwardly projecting anchoring elements, the number corresponding to a predetermined number of commutator segments, whereby the metal body is pressed in a press mold with a pressed material into a commutator blank and later is divided into individual laminae, characterized in that the division of the metal body of the commutator blank is performed before the cooling of the same.

United States Patent [191 Wiirner et al.

[111 3,902,241 1 Sept. 2, 1975 METHOD OF MANUFACTURING PRESSED MATERIALCOMMUTATORS [75] Inventors: Lothar Wo'rner, Stuttgart; Heinz Gerlach,Ehningen, both of Germany [73] Assignee: Firma Krautt & Bux A.G.,Stuttgart,

Germany [22] Filed: June 5, 1974 211 App]. No.: 476,517

[30] Foreign Application Priority Data June 6, 1973 Germany 2328753 [52]US. Cl. 29/597; 29/418; 29/527.l; 264/139; 264/237; 264/269; 310/43;310/235 [51] Int. Cl. HOIR 43/08 [58] Field of Search 29/597, 418,527.1; 310/235, 236, 43; 264/139, 162, 237, 269,

[56] References Cited UNITED STATES PATENTS 1,993,966 3/1935 Kessler29/597 2,188,423 l/l940 Andrews 29/597 2,400,590 5/ 1946 Meyerhoeffer2,963,774 12/1960 Pike 29/597 Primary Examiner-Carl E. Hall Attorney,Agent, or Firm-Wigman & Cohen [57] ABSTRACT A method of manufacturingpressed material commutators comprising a hollow cylindrical shapedmetal body, which is provided with a number of axial oriented groups ofinwardly projecting anchoring elements, the number corresponding to apredetermined number of commutator segments, whereby the metal body ispressed in a press mold with a pressed material into a commutator blankand later is divided into individual laminae, characterized in that thedivision of the metal body of the commutator blank is performed beforethe cooling of the same.

2 Claims, 1 Drawing Figure METHOD OF MANUFACTURING PRESSED MATERIAILCOMMUTATORS The present invention relatesto a method of producingpressed material commutators, in general, and molded plasticcommutators, in particular, comprising a hollow cylindrically shapedmetal body, which is equipped with anumber, corresponding to the numberof commutatorsegments, of axially aligned groups of inwardly projectinganchoring elements, whereby the metal body is pressed or molded in apress or compression mold with an insulating material to produce acommutator blank, being preferably molded from a known plasticcomposition, and which blank is later divided into theindividual laminaeor plates.

Small commutators are frequently composed not of individual laminae, butrather of a hollow cylindrically shaped metal body, which is equippedwith a number, corresponding to the number of commutator segments, ofaxially aligned groups of inwardly projecting anchoring elements. Thesemetal bodies are made either from profiled copper tube, which forexample has been profiled in an extrusionand drawing-process and fromwhich the individual metal bodies are separated in correspondingappropriate lengths, or they are made from a profiled band or strip,which has been profiled from a preliminarily shaped band or from stockmaterial by rolling by rollers, and from which, sections correspondingrespectively to the peripheral length of the commutator, are cut,separated and rolled into the hollow cylindrically shaped metal bodies.By the production of commutators with hooks for the windings, the lastmentioned method is more economical, since the section of the metalbody, which has the twisted hooks, can be manufactured with aconservation of material with the rollers by means of a correspondingdisplacement of material during rolling, whereas with the use of aprofiled copper tube, it must be produced from a correspondinglongitudinal section of this tube by a cutting removal of material.

The hollow cylindrically shaped metal bodies are heated and pressed orfilled under pressure, in a press or compression mold with a heatedinsulating material customary therefor, into a commutator blank, whichas a rule already has the receiving bore. With these commutator blanks,the annular shaped metal body is divided into the individual laminae bysawing between the longitudinal ribs with the anchoring elements, i.e.,between the groups of the anchoring elements.

During cooling of the heated and compressed commutator blank, thecontraction of the insulating mate rial body is larger than that of themetal body. Thereby the insulating material body loosens or releasesitself somewhat from the metal body, so that after the division of themetal body into the individual laminae, these no longer are rigidlyanchored in the insulating material body. By the use of an adhesiveinsulating material, the danger of the loosening of the laminae isreduced, however instead there occurs in the insulating body a formationof cracks originating from the bore side of the commutator. Bothoccurences influence the strength, solidity and durability of thefinished commutator to a considerable degree.

Accordingly it is an object and task of the present invention to providea method of manufacturing pressed material commutators by which theabove-mentioned disadvantageous occurences do not occur.

This object and task is solved by the present invention by a method withthe aforementioned method steps, in which the division of the metal bodyof the commutator is performed before the cooling of the insulatingmaterial thereof. Accordingly, there is no longer present, during thecooling of the commutator, a metal body closed in the circumferentialdirection, so that, of the individual laminae which are now separatedfrom one another, the contraction or shrinkage in the radial directionoccurring during the cooling of the insulating material body can followwithout any further consequences. In this manner, the loosening of thelaminae and the occurrence of cracks in the insulating material bodycharacteristic of the prior art are avoided.

Accordingly, a further object of the present invention is to provide amethod of manufacturing pressed material commutators comprising a hollowcylindrically shaped metal body, which is provided with a number ofaxially oriented groups of inwardly projecting anchoring elements, thenumber corresponding to a predetermined number of commutator segments,whereby the metal body is pressed in a press mold with a pressedmaterial into a commutator blank and later is divided into individuallaminae, and characterized by the step of performing the division of themetal body of the commutator blank prior to significant cooling of thepressed material.

It is another object of the present invention to provide a method forthe production of pressed material commutators in accordance with theabove-mentioned objective, and further wherein the metal body of thecommutator blank is suddenly cooled, chilled or quenched by a coolingmeans or medium prior to the subdivision into the laminae.

The last mentioned object and method therefor thus in a moreadvantageous manner can be yet thereby favored in that the metal body ofthe commutator blank is cooled suddenly, chilled or quenched prior tothe division into the laminae, by means of any suitable cooling means orcooling medium known per se.

In this manner the metal body which is connected intimately in the hotpressing condition with the insulating material body is additionallyshrunk-on the not suddenly cooled and therefore slower coolinginsulating material body. Thus, the anchoring of the laminae, which aresubsequently separated from each other, is still further improved.

For the tempering or annealing of the pressed material commutatorconnected in general to the division of the metal body in the individuallaminae the method in accordance with the present invention likewise isof advantage, since a loosening between the laminae and the insulatingmaterial body and/or a formation of cracks in the insulating materialbody neither occurs nor develops, which otherwise, during tempering orannealing of the entire commutator, could worsen.

With the above and other objects in view the present invention willbecome further understood in connection with the following detaileddescription of the drawing of which the only FIGURE is a partlysectioned perspective view of a finished commutator in accordance withthe present invention.

Referring now to the drawing, a finished commutator 1 is illustrated.The hollow cylindrical metal body 2 is divided into a plurality oflaminae or plates 2a prior to the cooling of the same.

Each laminae is formed with a plurality of axially oriented anchoringelements 3, whereby each of the individual laminae 2a is anchored in theinsulating body 4 which has a central receiving bore 5.

While we have described a preferred method of the present invention, itis to be understood that this description is not presented in anylimiting sense.

We claim:

1. A method of manufacturing pressed material commutators comprising ahollow cylindrically shaped metal body, which is provided with a numberof axially oriented groups of inwardly projecting anchoring elements,said number corresponding to a predetermined number of commutatorsegments, comprising the steps of:

molding an insulating material into an insulating body joined to and atleastpartially within said metal body in a mold under heat and pressureto form a heated commutator blank;

subsequently dividing said metal body into a plurality of individuallamina held together in spaced relationship by said insulating body, thedividing step occurring prior to any significant cooling of theinsulating material; and

subsequently cooling said commutator blank after said metal body hasbeen divided into said plurality of individual lamina.

2. The method of manufacturing pressed material commutators, inaccordance with claim 1, further comprising the step of:

suddenly rapidly cooling, by a cooling medium, said metal body of saidcommutator blank prior to the step of dividing said metal body into saidplurality of individual lamina.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. I 3,902, 241 DATED September 2, 1975 INVENTOR(S) 1 Lothar Worner and HeinzGerlach It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

In the heading of the patent, please change the number of the GermanForeign Priority Application to --P 23 28 753. 8- rather than "23287.53".

Please change the assignee's name from "Firma Krautt & Bux A-G." toFirma Kautt & Bux KG.

Signed and Scaled this A nest:

RUTH. C. MAISON I C. MARSHALL DANN 8 m Commissioner ofParenl: andTrademark:

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIQN PATENT NO. 3, 902,241 DATED September 2, 1975 INVENTOR(S) Lothar Worner and Heinz GerlachIt is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

In the heading of the patent, please change the number of the GermanForeign Priority Application to P 23 28 753. 8-- rather than 23287. 53".

Please change the assignee's name from "Firma Krautt & Bux A-G." toFirma Kautt & Bux KG,

-Thirteenth Day 0? July 1976 [SEAL] A ttest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner ofPaIentsand Trademarks

1. A method of manufacturing pressed material commutators comprising ahollow cylindrically shaped metal body, which is provided with a numberof axially oriented groups of inwardly projecting anchoring elements,said number corresponding to a predetermined number of commutatorsegments, comprising the steps of: molding an insulating material intoan insulating body joined to and at least partially within said metalbody in a mold under heat and pressure to form a heated commutatorblank; subsequently dividing said metal body into a plurality ofindividual lamina held together in spaced relationship by saidinsulating body, the dividing step occurring prior to any significantcooling of the insulating material; and subsequently cooling saidcommutator blank after said metal body has been divided into saidplurality of individual lamina.
 2. The method of manufacturing pressedmaterial commutators, in accordance with claim 1, further comprising thestep of: suddenly rapidly cooling, by a cooling medium, said metal bodyof said commutator blank prior to the step of dividing said metal bodyinto said plurality of individual lamina.